The successful commercial exploitation of meat-containing intermediate moisture pet foods emanating from the inventive development of Burgess et al. (Canadian Pat. No. 739,897) has spurred the food industry to adapt the basic principles set forth toward further product and process improvements--mainly in the nature of preparing pet foods in forms other than the original room temperature storage stable hamburger patty disclosed by Burgess et al.
As recognized by those in the meat industry, tender and juicy meat chunks are characterized by having a significant amount of fat distribution throughout the lean or red meat portions in a randomized fashion producing the chunk with a mottled or marbleized appearance. The prior art, cognizant of the appeal to the owner of pets of the marbled appearance of meat due to the association of this feature with tenderness and juiciness, have attempted to incorporate a marbled appearance in the product made from formulation and produced to resemble raw beef chunks.
Canadian Pat. No. 842,164--Bone discloses a method for manufacture of a meat-containing semi-moist pet food simulating marbleized red meat chunks containing a significant level (71/2 to 25% by weight of the red meat formulation) of a caseinate salt binder. The method of Bone involves laminating red meat and white "fat" layers or sheets of the semi-moist formulations; forming loaves of the laminate; and then subdividing the loaves into small size cubes.
Charter, in U.S. Pat. No. 3,765,902, mentions that the process of Bone suffers from the disadvantage of requiring excessive personal attention, and discloses apparatus for producing a caseinate binder product similar to that of Bone with a minimum of human control.
The methods of Bone and Charter both apparently rely upon the caseinate adhesive to provide an extrudate which is sufficiently tacky, or sticky, at temperatures above about 120.degree. F. to effect proper joining of the red and white portions to form an integral mass having substantially distinct interface between the portions.